Study protocol for a process evaluation of a cluster randomised controlled trial to reduce potentially inappropriate prescribing and polypharmacy in patients with multimorbidity in Irish primary care (SPPiRE) [version 2; peer review: 2 approved]

Background: Multimorbidity (the presence of two or more chronic conditions) is associated with poorer health outcomes, particularly for patients with significant polypharmacy (≥15 medications), due to the higher risk of adverse events and drug interactions. The SPPiRE study will assess the effectiveness of a complex intervention to support general practitioners (GPs) to reduce potentially inappropriate prescribing and consider deprescribing in older people with multimorbidity and significant polypharmacy. The aim of the SPPiRE process evaluation is to understand how and why the intervention is effective or ineffective and to explore the potential for system wide implementation of the intervention using the Medical Research Council general themes of context, implementation and mechanism of impact. Methods: The SPPiRE study is a clustered randomised controlled trial (RCT), aiming to recruit 55 general practices and 400 patients (≥65 years) on ≥15 medications throughout the Republic of Ireland. This mixed-methods process evaluation of the SPPiRE study will integrate both quantitative and qualitative data. Quantitative data will be collected on use of the intervention elements and from GP questionnaires. Qualitative data will be collected from semi-structured telephone interviews with all intervention GPs and a purposeful sample of patients from intervention practices. The topic guide will explore barriers and facilitators to participation and implementation of the intervention. Quantitative data will be analysed using descriptive statistics. Interviews will be transcribed and analysed using thematic analysis. Quantitative and qualitative data will be then be integrated. Discussion: The SPPiRE cluster RCT will provide evidence regarding the effectiveness and practicability of delivering a structured medication review in reducing polypharmacy and potentially inappropriate prescribing for patients with multimorbidity. This process evaluation will provide information on how the intervention was implemented, how it was or was not effective and the potential for a system wide implementation. Trial registration: ISRCTN 12752680, registration: 20/10/2016.